The present invention relates to a pneumatic tire, more particularly to an asymmetric tread reinforcing structure capable of improving high-speed durability, without sacrificing ride comfort.
In general, a radial tire for high speed running is provided in the tread portion with a belt (cross-ply breaker) for reinforcing the tread portion and a radially outer band for preventing the belt from lifting to provide high-speed durability for the tire.
In recent years, in order to improve the high-speed durability, such a band is formed by winding a high-modulus organic fiber cord or cords across the entire width of the radially inner belt structure. In such tire structure, however, due to the high modulus organic fiber cord band, ride comfort is liable to deteriorate.
On the other hand, Japanese Patent Application Publication No. P2009-137495A (corresponding to United States Patent Application Publication No. US2010-319825A1) discloses a pneumatic tire provided with a narrow single-ply band made of a high modulus cord and a wide single-ply band made of a low modulus cord which are disposed side-by-side on the radially outside of a tread reinforcing belt. In such tire structure, however, there is room for improvement from a point of view of simultaneous pursuit of ride comfort and high-speed durability.